Vertically stored telescoping lip leveler

ABSTRACT

The present invention is a vertically stored dock leveler with a telescoping lip that selectively extends and retracts through a range positions relative to the deck. The lip is held and guided by a deck frame carriage. When the deck is raised and lowered, the lip is extended and retracted by an electro-hydraulic control system. When the deck reaches a preselected incline position, the lip is fully extended. Sensors on the underside of the deck determine the incline position of the deck and when the lip is retracted. The leveler is then lowered until the lip engages and rests on the bed of the trailer. Similarly, when the deck is raised for storage and reaches the preselected incline position, the lip is fully retracted prior to returning to its stored position. The telescoping lip is selectively moveable to a range of partially extended position to facilitate end loading a trailer.

TECHNICAL FIELD OF THE INVENTION

This invention relates to a vertically stored dock leveler with atelescoping lip that is fully extended for normal loading of a trailer,partially extended to end load the trailer, and retracted for storage.

BACKGROUND OF THE INVENTION

Dock levelers are used to transfer goods between a building and a trucktrailer. They bridge the gap between the building floor to the bed ofthe trailer or similar carrier. Levelers include a frame or supportstructure to mount it in a pit of a loading dock. The rear end of theleveler is hinged to the building floor. The opposite end of the levelerhas an extendable lip plate that engages the trailer bed. A doorway ispositioned over the loading dock and its pit. The doorway is opened toload and unload a trailer, and closed when the dock stall is not in use.Conventional levelers are designed to store in either a horizontal orvertical position. Horizontally stored levelers are adapted to move froma generally horizontal position where the upper surface of the deck isflush with the surface of the building floor to a second generallyinclined position to provide a ramp between the bed of the truck and thedock floor. When stored in the pit, the door seals against the top ofthe loading dock deck. The door does not extend to the bottom of thepit. Hot or cold air, humidity, dust and insects can enter the buildingvia the pit. Vertically stored levelers are adapted to move from agenerally vertical stored position to a generally inclined position toprovide a ramp between the bed of the truck trailer and the dock floor.When stored, these levelers are located entirely inside the building sothat the overhead door can seal off the pit to seal the interior of thebuilding from thermal losses, humidity, dust, insects, etc. Verticallystored levelers are particularly suited for docks handling food andother refrigerated goods.

Various mechanisms have been developed for extending and retracting thelip of a dock leveler during operation. Two common types are pivotallyextending the lip and telescopically extending the lip. When the lipextends pivotally, the lip extends from its pendant stored position toits extended position when the ramp is raised or when the operator walksthe ramp down. Examples of pivotally extended lips are disclosed in U.S.Pat. No. 3,137,017 to Pfleger, U.S. Pat. No. 3,997,932 to Artzberger,U.S. Pat. No. 4,398,315 to Driear, U.S. Pat. No. 5,475,888 to Massey,and U.S. Pat. Nos. 6,834,409 and 7,013,519 to Gleason, the disclosuresof which are incorporated by reference. When the lip extendstelescopically, the lip extends from its stored position under the deckof the leveler to its extended position. Examples of telescopicallyextended lips are disclosed in U.S. Pat. Nos. 5,001,799 and 5,396,676 toAlexander, U.S. Pat. No. 5,450,643 to Warner and U.S. Pat. No. 5,586,355to Metz, the disclosures of which are incorporated by reference.

Conventional vertically stored levelers have a hinged lip. The lip fullyextends to rest on a trailer bed when loading or unloading a trailer.When extended, the lip is flush with and relatively parallel to the deckof the leveler. When cargo has been loaded or unloaded, the deck israised to remove the lip from the trailer. As the deck rises, the lipmoves to a pendent position so that when the deck is vertically stored,the lip is roughly perpendicular to the deck.

A problem with conventional vertically stored dock levelers is endloading a trailer. The lip is extended up to two feet into the trailer.Cargo cannot be placed at the end of the trailer without setting thecargo on the lip of the leveler. Placing cargo on the lip inhibitsraising the leveler to remove the lip from the trailer. Thus, to endload the trailer, the deck must be raised and lowered so that the liphangs pendent to fit in a gap between end of the dock floor and thetrailer bed as shown in FIG. 14. This extra step takes time. A workermust park and get off a forklift to operate the dock leveler. The deckhas to be raised, and pneumatic cylinders must discharge to allow thehinged lip to hang pendent. Then the deck has to be lowered to aposition that brings its front end even with the trailer bed. Theseadditional steps reduce dock efficiency. They also cause additional wearand tear on the leveler, which increases the frequency of routinemaintenance. If a dock worker does not wait for the lip to hang entirelypendent, the tip of the lip can strike, gouge or otherwise damage thetrailer. In addition, when unloading an already end loaded trailer, thelip cannot be extended to bridge the gap between the trailer bed anddock floor. The cargo at the end of the trailer prevents the deploymentof the lip. The cargo at the end of the trailer must first be unloadedwithout the use of the lip. The leveler is then raised and lowered todeploy the lip into the trailer to further unload the trailer.

Another problem with conventional vertically stored dock levelers duringend loading is that the pendent lip does not bridge the gap between thetrailer bed and dock floor. The exposed gap can allow a forklift wheelto inadvertently be driven or slip into this gap. Cargo can fall off theforklift and be damaged, and the time needed to lift the forklift out ofthe gap reduces dock efficiency. The exposed gap also poses a potentialsafety concern for dock workers who can inadvertently trip on or stepinto this gap. Goods, tools and other items can also fall through thegap to further reduce dock efficiency. Moving the lip to a pendantposition also frequently interferes with the operation of the vehiclerestraint securing the trailer to the loading dock. The restraintfrequently needs to be disengaged to allow the lip to hang pendent.Disengaging the vehicle restraint allows inadvertent and unsafe movementof the truck while workers are still end loading the trailer.

A further problem with vertically stored levelers is controlling themovement of the deck relative to the movement of the hinged lip. Theleveler must clear the overhead door. The deck should not be raised toits vertical position until the hinged lip moves to its pendentposition. The total height of the leveler must be shorter than theheight of the door opening. The total height of a vertically storedleveler with the lip extended can exceed 9 to 12 feet, which can exceedthe height of the door opening, or impact ventilation ducts, piping,wiring, or other components in the interior of the loading dock.Although loading dock doors are designed to accommodate verticallystored levelers when the lip is pendent, they may not accommodate theleveler when its lip is extended. A leveler with an extended lip canstrike and damage the overhead door or the components in the interior ofthe dock.

A still further problem with conventional dock levelers is keeping thecontrols and the wiring for the controls as simple as possible.Complicated control system wiring is difficult to install, and canresult in installation and maintenance errors. Components that have tobe wired a particular way are more complicated, and can lead to wiresbeing inadvertently crossed.

A still further problem with conventional dock levelers is the use oflimit switches to control the raising and lowering of the deck. Thelimit switches are typically placed at or near the perimeter of thedoorway, which is an inherently busy area of a loading dock. Theswitches can be inadvertently bumped and result in a levelermalfunction.

The present invention is intended to solve these and other problems.

BRIEF DESCRIPTION OF THE INVENTION

The present invention pertains to a vertically stored dock leveler witha telescoping lip that selectively extends and retracts through a rangepositions relative to the deck. The lip is held and guided by a deckframe carriage. When the deck is raised and lowered, the lip is extendedand retracted by an electro-hydraulic control system. When the deckreaches a preselected incline position, the lip is fully extended.Sensors on the underside of the deck determine the incline position ofthe deck and when the lip is retracted. The leveler is then lowereduntil the lip engages and rests on the bed of the trailer. Similarly,when the deck is raised for storage and reaches the preselected inclineposition, the lip is fully retracted prior to returning to its storedposition. The telescoping lip is selectively moveable through a range ofpartially extended position to facilitate end loading a trailer.

One advantage of the present vertically stored leveler is loading dockefficiency. When loading a trailer, the lip is extended over the trailerbed up to two feet. When cargo is ready to be placed at the end of thetrailer, the lip is partially retracted without removing it from thetrailer so that only a few inches of the lip extends over the trailerbed. Similarly, when cargo at the end of the trailer is being unloaded,the lip is only partially extended a few inches into and over thetrailer bed. The operation of the leveler does not waste time raisingand lowering the deck to move the lip between pendent and extendedpositions. This improves dock efficiency and minimizes extra wear andtear on the leveler. In addition, the lip remains relatively in-linewith the leveler deck, to minimize or avoid any risk of damage to thetrailer to perform an end load.

Another advantage of the present vertically stored telescoping lipleveler is end loading safety. When cargo is being placed on or removedfrom the rear end of the trailer, the lip can be moved to a partiallyextended position so that only a few inches of the lip extends over thetrailer bed. The lip bridges the gap between the dock and the trailer sothat the forklift wheel will not inadvertently drop into the gap, whichcan cause cargo to fall off the forklift, and which requires the heavyforklift to be pulled from the gap. Workers also do not run the risk ofinadvertently stepping into the gap. The deployment of the lip over thegap also prevent goods or debris from falling through the gap betweenthe dock and the trailer during end loading and unloading. Therestraining device remains engaged to capture the trailer RIG to preventits inadvertent movement when dock workers are end loading.

A further advantage of the present vertically stored telescoping lipleveler is controlled movement of the deck and lip. When the deck isbeing lowered from storage and reaches the preselected inclinedposition, the lip automatically extends. Similarly, when the deck isbeing raised for storage and reaches the preselected inclined position,the lip automatically retracts. Unless the control system is overridden,the deck cannot be raised to its vertical stored position until thehinged lip moves to its retracted position. Similarly, unless thecontrol system is overridden, the lip cannot be extended until the deckis lowered to the preselected incline position. This control helpsensure that the leveler clears and does not damage the overhead door orany ventilation ducts, piping, wiring, or other components in theinterior of the loading dock.

A still further advantage of the present vertically stored telescopinglip leveler is control wiring simplicity. The position sensor isremarkably easy wire to the control system. The sensor works independentof how the input and out put wires are connected to the control system.Crossing the sensor wires will not result in operation error.

A still further advantage of the present vertically stored telescopinglip leveler is operation reliability. The position sensor is remarkablyreliably and is installed at a location on the underside of the deckwhere it is unlikely to be inadvertently bumped in the busy workenvironment of a loading dock. Limit switches located at or near hightraffic areas along the perimeter of the loading dock doorway areavoided.

Other aspects and advantages of the invention will become apparent uponmaking reference to the specification, claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the outside of a loading dock buildingequipped with the present vertically stored dock leveler.

FIG. 2 is a perspective view of the inside of a loading dock buildingequipped with the present vertically stored dock leveler.

FIG. 3 is a perspective view of the underside of the present verticallystored dock leveler in its raised vertical storage position with the lipretracted.

FIG. 4 is a perspective view of the underside of the present verticallystored dock leveler in a lowered position with the lip extended.

FIG. 5 is a side view showing the dock leveler lowered to a lipextending position where the retracted lip moves to its fully extendedposition.

FIG. 6 is a side view showing the dock leveler with its fully extendedlip lowered into engagement with the trailer bed.

FIG. 7 is a side view showing the range of motion of the dock levelerwith its fully extended lip is engaged with a trailer bed.

FIG. 8 is a side view showing the dock leveler with the lip partiallyretracted to facilitate trailer end loading.

FIG. 9 is a sectional view taken along line 9-9 of FIG. 3 showing theguide carriage of the deck frame for holding and guiding the lipassembly.

FIG. 10 is a partial perspective view taken along line 10-10 of FIG. 3showing the guide carriage of the deck frame for supporting and guidingthe lip assembly.

FIG. 11 is an enlarged view of the position sensor and magnet shown inFIG. 3 with a portion cut away to show the yoke roller riding on theguide track.

FIG. 12 is an electric schematic of the vertically stored leveler withtelescoping lip.

FIG. 13 is a hydraulic schematic of the vertically stored leveler withtelescoping lip.

FIG. 14 is a side view of a conventional vertically stored dock levelerwith a hinged lip hanging pendent to allow a forklift to end load atrailer with the forklift wheels approaching a gap between the trailerand dock floor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

While this invention is susceptible of embodiment in many differentforms, the drawings show and the specification describes in detail apreferred embodiment of the invention. It should be understood that thedrawings and specification are to be considered an exemplification ofthe principles of the invention. They are not intended to limit thebroad aspects of the invention to the embodiment illustrated.

Loading docks 5 have a generally flat, horizontal, elevated floorsurface 6 that extends from a generally vertical exterior front wall 7into the interior of the building 8. The front wall 7 includes a vehiclerestraint 10 with a restraining or hooking mechanism 11 that isselectively moved from a released position to a locked position 12. Thefront wall 7 also includes bumpers 9 to engage the trailer when it backsinto the dock 5. The front wall 7 extends from the elevated dock floor 6to the paved drive or ground surface 15 upon which the trailer travels.The loading dock 5 has a pit 20 of sufficient depth to accommodate adock leveler when it is lowered as shown in FIG. 1. The pit 20 has afloor 22, opposed sidewalls 23, rear wall 24, and open front. The pitfloor 22 is generally horizontal or slightly sloped for drainage, and isspaced a desired distance from the dock floor 7. The pit walls 24 aregenerally vertical and normal to floor surfaces 6 and 22. The loadingdock building 8 has a doorway 25 set back from the front wall 7 of theloading dock 5 and forward from the rear wall 24 of the pit 20. Anoverhead door 26 is used to selectively open and close the doorway 25.The vertically stored dock leveler is positioned at the rear of the pit20 behind the doorway 25 and overhead door 26. The entire verticallystored leveler is inside the building 8 when the door 25 is closed. Theoverhead door seals against the frame of the doorway 25, pit sidewalls23 and pit floor 22. The overhead door 26 seals the doorway 25 when thedock is not in use, and is opened by a dock worker when a trailer 30backs up to the dock 5 for loading or unloading.

The loading dock 5 is designed to facilitate access to a trailer 30 of atruck or other carrier as shown in FIG. 5-8. The trailer 30 has a bed 32upon which cargo items 35 are placed for transport. The trailer bed 32is spaced above the road or drive surface 15 on which the trailer 30travels. The dock floor 6 is spaced a desired distance above itsadjacent driveway or approach 15 so that a trailer bed 32 is somewhatnear the level of the dock floor 6 when the rear end of the trailer 30backs up to the front 7 of the dock 5. The trailer 30 is secured to thefront wall 7 by the restraining device 10 by selectively moving itsrestraining or hooking device 11 from a release position to a lockedposition 12 to capture the rear impact guard (RIG) 38 of the trailer.The pit floor 22 is elevated a desired height above the driveway 15, butcould be even with or lower than the driveway depending on theparticular circumstance without departing from the broad aspects of theinvention. The height of the trailer bed 32 relative to the dock floor 6depends on a variety of factors that include the particular trailer 30involved and the weight of the cargo item or items 35 on the trailer.The trailer bed 32 rises and falls relative to the dock floor 6 as cargoitems 35 are placed on or removed from the trailer 30.

The present invention relates to a vertically stored dock levelergenerally indicated by reference number 50 and shown in FIGS. 1-4. Thedock leveler 40 has a variety of components including a mounting frameassembly 60, a deck and lip assembly 70 with a telescoping lip assembly90, and deck and lip positioning mechanisms 110 and 120. The componentsare robustly designed to support the weight of the deck and lip assembly70 and the loads it is intended to carry when forklifts and the likecarry cargo items 35 over the leveler 50. The components are generallymade of industrial grade steel or materials of similar strength anddurability. The components may be painted, coated or otherwise treatedto inhibit rust or corrosion.

The mounting frame assembly 60 is located along the floor 22 and rearwall 24 of the pit 20. The frame assembly 60 has a rear end, andincludes a base frame 61 that is bolted or otherwise rigidly anchored tothe pit floor 22, and a vertical riser frame 65 that is similarlyanchored to the pit rear wall 24. The base frame 61 spans the majorityof the width of the pit 20. The riser frame 65 is located along the pitrear wall 24, and are preferably welded or otherwise rigidly secured tothe rear end of the base frame 61. The riser frame 65 includes two ormore vertical beams joined together by lower and upper mounting channels62 and 66. The upper mounting channel 66 is aligned against and anchoredto one or both of the top of the pit rear wall 24 and the dock floor 6.The riser 65 is rigidly secured to the upper mount 66 to firmly supporta fixed tubular hinge or pivot mount 67 for pivotally supporting thedeck and lip assembly 70. A pivot bracket 63 extends forward from to thebase frame 61 to supportably receive a hydraulic deck drive cylinderspaced a predetermined distance from the rear wall 24 of the pit 20. Themounting frame 60 is preferably permanently attached to case in steel inthe building floor at its rear pivot end.

The deck and lip assembly 70 includes a deck assembly 71 and atelescoping lip assembly 100 as best shown in FIGS. 3 and 4. The deckassembly 71 includes a deck frame 72, lip retaining area 77, deck 80 andlip support carriage 90. The entire deck and lip assembly 70 is movablethrough a range of inclined positions as discussed below. The decksupport frame 72 has six relatively evenly spaced, parallel beams 73 andside plates 74 that are welded or otherwise rigidly joined together by arear plate 75. The deck support beams 73 extend forward about ⅔ thelength of the deck 80 to the rear end 78 of the lip retaining area 77.The beams 73 do not extend into the lip retaining area 77. The front endof each beam 73 is welded or otherwise rigidly secured to the underside84 of the deck 80 via two gussets. The top of the outside or rearsurface of the rear plate 75 is firmly and pivotally secured to thehinge 67 at the top of the support frame risers 65 and upper mountingchannel 66. The side plates 74 include a pinch guard 79.

The deck 80 is preferably formed from a sheet or plate of metal 81. Thedeck plate 81 has a predetermined length of preferably about 5 to 7 feetbetween its parallel rear and front ends 82 and 83. The rear end 82 isflushly aligned with the rear plate 75, and its front end 83 extendsbeyond the support beams 73. The deck plate 81 has a predetermined widthbetween its outermost side edges 81 a, and a thickness defined by itsparallel lower and upper surfaces 84 and 85. The lower surface 84 iswelded or otherwise rigidly secured to the frame 72, and its uppersurface 85 is generally flat and free and clear of obstructions. Sideguards 86 are fixed to the sides of the deck plate 81. The deck and lipassembly 70 is pivotally secured to hinge 67 so that the upper surface85 of the deck plate 81 is aligned parallel to the dock floor 6 when thedeck 80 is lowered.

The lip carriage 90 includes two support and guide rails 92. One rail 92is secured to the inside surface of each side plate 74 of the deck frame72. Each elongated rail 92 has a generally linear shape and is about twofeet long. The rails 92 have a uniform rectangular cross-sectional shapealong their length, to provide flat upper and inner surfaces. The uppersurface of each rail 92 is uniformly spaced downwardly from and roughlyparallel to the deck plate 81. The carriage assembly 90 also includestwo guide tracks 93. Each guide track or roller trap 93 extends forwardfrom the rear header plate 75. Its rear end is bolted to plate 75, andits front end is bolted to a bracket welded to the underside 84 of thedeck plate 81. The lip support and guide assembly or carriage 90 alsoincludes a crossbar 94. The crossbar 94 spans the width of the deck 80and is welded or otherwise rigidly secured to the lower ends of the deckframe side plates 74. The crossbar 94 is spaced a predetermined distancefrom the deck plate 81 to accommodate the telescoping lip assembly 100as discussed below. The crossbar 94 is located forward of the rearheader plate 75 about ⅔ the length of the deck 80. The crossbar 94 addslateral stiffness to prevent roller binding.

The deck assembly 71 has a position sensor 87 that senses the angle ordegree of incline of the deck 80. The incline sensor 87 is placed in anout of the way location on the deck frame 72 or deck, such as on theside of one of the support beams 73 under the deck 80. The sensor 87 ispreferably a Hall Effect sensor that sends a digital signal. The sensor87 works in unison with a magnet 87. The sensor 87 and magnet 88 areused to detect when the lip assembly 100 has returned to its retractedposition 121. The sensor 87 is in electrical communication with the dockleveler control systems 150 via a wire 89 as discussed below.

The deck assembly 71 includes a maintenance lock mechanism 95 toward itsrear end 82. The lock mechanism 95 includes two parallel slotted plates96 rigidly secured to the deck frame 72, and a safety bar 97 pivotallysecured to the mounting frame 61. The safety bar 97 includes a lockingstrut 98 that travels in the slots o plates 96. The vertically storedleveler 50 is locked into its vertical position by inserting a pin (notshown) that locks the leveler into its vertical position 70A so thatmaintenance can be safely performed.

The telescoping lip assembly 100 has a lip plate 101, header plate 106and lugs 107. The lip plate 101 has a generally rectangular shape. Itslength is defined by its parallel inner end 102 and its outer or freeend 103. Its width is defined by its parallel side edges. The side edgesof the lip plate 101 are in substantial registry or alignment with sideedges 81 a of the deck 80, and are received between and slightlyinwardly offset from the side plates 74 of the deck frame 72. The lipplate 101 has a predetermined thickness defined by its generallyparallel lower and upper surfaces 104 and 105. The upper surface 105 ofthe free end 103 is beveled or slightly sloped toward the lower surface104. The inner end 102 of the lip plate 101 is joined to the top of itsheadboard or header plate 106. This connection is strengthened by anumber of lugs 107 welded to the lower surface 104 of the lip plate 101and front of its header plate 106. The header plate 106 is heldsubstantially perpendicular to the deck plate 81. Each lug 107 forms an85° angle to hold the lip plate 101 at an 85° angle relative to itsheader plate 106, so that the lip plate is at a 5° downward anglerelative to the deck plate 81. The lip plate 101 is preferablydownwardly sloped 5° relative to the deck plate 81 to facilitateengagement with a trailer bed 32 when the trailer bed is elevatedslightly above the dock floor 6 as shown in FIGS. 5 and 6.

The lip assembly 100 has guide and support components 110 totelescopically join it to the deck frame 72 and support carriage 90 toallow its linear movement. These guide and support components 110include two sets of lip guide beams 111. One set of guide beams 111 islocated on each side of the deck 80. Each set included two uniformlyspaced guide beams 111. Each elongated lip beam 111 is linear shape andhas a preferably tubular shape for strength. Each beam 111 is welded orotherwise rigidly secured to the rear surface of the lip header plate106, and extends perpendicular to the header plate 106. Each set ofbeams 111 straddle one of the lip guide tracks 93 of the lip support andguide carriage 90. The guide tracks 93 and beams 111 are linearlyaligned. The upper surface of each beam 111 is planar to and spacedabout ⅛ inch from the underside 104 of the lip plate 101. The uppersurface of each track 93 is planar to and spaced about 2½ inches fromthe underside 104 of the lip plate 101.

The lip guide and support components 110 include several rollers tomovingly support and smoothly guide the telescoping lip assembly 100.Each side of the lip header plate 106 has a rigidly secured mountingblock 113. Each mounting block 113 rotatingly holds a vertically alignedroller 114 that rollingly engages the upper surface of its correspondingguide rail 92 to movingly support the weight of the lip assembly 100.These weight-bearing rollers 114 ride on the guide rails 92 to supportthe majority of the weight of the lip assembly 100, and transfer thatweight to the deck frame 72 via the guide rails 92 of the supportcarriage 90. Each mounting block 113 also rotatingly holds ahorizontally aligned roller 115 that rollingly engages the side surfaceof its corresponding guide rail 92 to maintain the registered alignmentof the lip plate 101 with the deck plate 81. The alignment rollers 115also maintain the engagement of the weight bearing rollers 114 with thelip guide rails 92. A first set of two rear brackets 116 rotatingly holdthird or weight-bearing yoke rollers 117. The bracket 116 is securedtoward the end of two adjacent guide beams 111 and straddles the guidetrack 93. Each yoke roller 117 rides on the upper surface of the guidetrack 93 to help movingly support the weight of the lip assembly 100. Asecond set of two rear bracket 118 rotatingly hold fourth or alignmentrollers 119. The bracket 118 is rigidly secured to the rear end of atleast one guide beam 111 in each set of the two sets of guide beams.Each guide roller 119 rollingly engages the side surface of itscorresponding guide track 93 to further maintain the registeredalignment of the lip plate 101 with the deck plate 81.

The guide and support components 110 are telescopically secured to thedeck frame 72 by the support carriage 90. The lip guide and supportcomponents 110 allow the lip assembly 100 and lip plate 101 to movealong a substantially linear path of travel 120 between a retractedposition 121 in the lip retaining area 77 as in FIGS. 1-4 and a fullyextended position 122 out of the lip retaining area 77 as in FIGS. 5-7.When fully extended 122, the rear or inner end 102 of the lip plate 101is just forward of and in linear alignment with the front end 83 of thedeck plate 81. The lip assembly 100 and lip plate 101 are also movableto any desired partially extended position 123 through a continuousrange of partially extended positions, such as for end loading of atrailer as in FIG. 8.

When in its retracted or stored position 121 as in FIG. 3, the free end103 of the lip plate 101 is in substantial registry with the front end83 of the deck plate 81. When the lip assembly 100 is in its retracted121, fully extended 122 or partially extended 123 positions as shown inFIGS. 3, 5 and 8, respectively, the upper surface 105 of the rear end102 of the lip plate 101 is slightly downwardly offset from the uppersurface 85 of the deck plate 81. The amount of the offset is slightlymore than the thickness of the deck plate 81. The amount of offset atfront end 103 of the lip plate 101 is slightly more given its 5° anglerelative to the deck plate 81 as best shown in FIG. 5. When fullyextended 112 and lowered into engagement with the trailer bed 32, thelip plate 101 shifts or rises slightly upward relative to the deck 80 toeliminate the offset between the lip plate 101 and the deck plate 81, sothat their upper surfaces 85 and 105 are flush as in FIGS. 6 and 7. Toperform an end load after the lip plate 101 has been resting on thetrailer bed 32, the deck 80 must be raised a slight amount equal to theabove noted offset to allow the lip plate 101 to retract underneath thedeck plate 81.

The lip support carriage 90 and lip assembly 100 are designed to helpsupport the front end 83 of the deck 81 when the lip is extended 122 or123 to load a trailer 30. When fully extended 112 and lowered intoengagement with the trailer bed 32 as in FIGS. 6 and 7, the rectangularlip guide beams 111 engage and support the front end 83 of the deckplate 81. The guide beams 111 are supported by the deck frame 72 and lipcarriage 90. The beams 111 are welded to the lip headboard 106, which issupported by the guide rails 92 of the carriage 90. When the lip plate101 is only partially extended for end loading as in FIG. 8, the lipplate 101 also provides support to the deck 81 further back from itsfront end 83. When in its vertically stored position 70A as in FIGS.1-3, the lip assembly 100 rests on the gussets at the front end of thedeck support beams 73. The gussets are best shown in FIG. 4.

The deck positioning mechanism 130 is shown in FIGS. 3 and 4 andillustrated in FIGS. 12 and 13. The deck positioning mechanism 130selectively raises and lowers the deck and lip assembly 70 through arange of positions 70A-D as shown in FIGS. 3-8. The deck positioningmechanism 130 is preferably hydraulic, and includes a conventional drivecylinder 131, drive rod 132, intake and outlet hoses 133, hydraulic pump135 and solenoid valve 137. One end of the hydraulic cylinder 131 ispivotally pinned to a bracket welded to the underside 84 of the deckplate 81. The drive rod 132 is pinned to the mounting bracket 63 of thebase frame 61. The cylinder 131 extends and retracts its drive rod 132to selectively rotate the deck and lip assembly 70 through its inclinepositions 70A-D by pivoting it up or down about hinge 67.

During operation, the deck positioning mechanism 130 sequentially movesthe deck and lip assembly 70 from a vertically stored position 70A as inFIGS. 1-3, down to a partially lowered lip extending position 70B as inFIGS. 4 and 5, and further down into engagement with the trailer bed 32through a range of trailer engaging positions 70C-D as in FIGS. 6 and 7.The range of trailer engaging positions including upper position 70C andlower position 70D.

The lip extension mechanism 140 is shown and illustrated in FIGS. 3, 4,12 and 13. The lip positioning mechanism 140 extends and retracts thelip assembly 100 and lip plate 101 when the leveler 50 reaches a presetangular position 70B as shown in FIG. 5. The lip extension mechanism 140is preferably hydraulic, and includes a drive cylinder 141, drive rod142, intake and outlet hoses 143 and solenoid valve 147. The mechanism140 shares the hydraulic pump 135 of the deck positioning mechanism 130.The lip drive rod 142 has a predetermined length of about two feet. Oneend of the hydraulic cylinder 141 is pivotally pinned to a bracketsecured to the rear header 75 of the deck frame 72. The drive rod 142 ispinned to a bracket secured to the rear header 106 of the lip assembly100. When the lip drive 140 is engaged, the lip drive rod 142 pushes orpulls the lip assembly 100 along its linear path of travel 100 into itsretracted, fully extended or partially extended positions 121-123.

During operation, the lip extension mechanism 140 selectively moves thelip 101 to its retracted position 121 when the lip is inclined above setposition 70B as in FIGS. 1-3. The lip extension mechanism 140 also movesthe lip 101 to its extended position 122 when the lip is inclined at orbelow set position 70B as in FIGS. 4-7. The lip extension mechanism 140also selectively moves the lip 101 to its partially position 123 toperform trailer end loading.

A control system 150 is provided to allow the dock workers to easilycontrol the operation of the leveler 50. The control system 150 includesa control panel 152 located inside the loading dock building 8 as shownin FIGS. 2, 12 and 13. The control panel 152 includes a circuit board153 in electrical communication with a programmed central processingunit (CPU) 154 and a number of dock leveler controls 160. The controls160 include an on/off switch (not shown) and a number of push buttons161-164. The on/off switch activates the control system 160, includingthe motor 135 to compress hydraulic fluid that will flow throughhydraulic lines 133 to the deck drive cylinder 131 and hydraulic lines143 to lip drive cylinder 141.

During operation, to return the leveler 50 to its vertically storedposition 70A as in FIG. 3, the dock worker engages and releases thefirst button 161. This causes the CPU 154 to place the deck liftsolenoid valve 137 in a state that extends the deck drive rod 132 andraises the deck 80 toward position 70B as in FIG. 5. When the deck 80reaches this incline position 70B as detected by position sensor 87, theCPU 154 places the lip solenoid valve 147 in a state that retracts lipdrive rod 142 and lip 101. The CPU 154 then moves the leveler 50 to itsstored position 70A. When the leveler 50 is vertically stored 70A, and adock worker engages and holds the second button 162, the CPU 154 placesthe deck lift solenoid valve 137 in a state that retracts deck driverode 132 and lowers the deck 80 to position 70B. When position sensor 87detects that the deck has reached this inclined position 70B, the CPU154 places the lip solenoid valve 147 in a state that extends the lipdrive rod 142 and the lip 101 as in FIGS. 12 and 13. The CPU 154 thencontinues to retract deck drive rod 132 to lower the deck until the lip101 engages the bed 32 of a trailer 30 parked in the loading bay 5 as inFIGS. 6 and 7. Engaging and holding a third button 163 caused the CPU154 to place the lip solenoid valve 147 in a state that extends the lipdrive rod 142 and lip 101 to either partially or fully extend the lip101 depending on when the button 163 is released. Similarly, engagingand holding a fourth button 164 caused the CPU 154 to place the lipsolenoid valve 147 in a state that retracts the lip drive rod 142 andlip 101 either partially or fully depending on when the button 164 isreleased.

While the invention has been described with reference to a preferredembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the broader aspects of the invention.

I claim:
 1. A vertically stored telescoping lip leveler for forming abridge between a floor of a loading dock and a trailer bed, the loadingdock having a pit, said vertically stored telescoping lip levelercomprising: a mounting frame secured to the pit of the loading dock; adeck assembly including a deck plate, front and hinged ends, outermostside edges, deck frame, lip retaining area and lip support carriage,said deck frame having a plurality of deck beams and side platespositioned under said deck plate, said side plates extending downwardlyproximal to said outermost side edges, said deck beams extending fromproximal said hinged end toward said front end and terminating beforesaid lip retaining area, and said side plates extending from proximalsaid hinged end to proximal said front end, said lip support carriagehaving a lip guide rail secured to each of said side plates, each ofsaid lip guide rails extending along said lip retaining area under saiddeck plate, said hinged end being pivotally secured to said mountingframe, said lip retaining area being proximal said front end, and saiddeck assembly being movable through a range of inclined positionsincluding a substantially vertically stored position, a preset inclineposition and a trailer engaging position, said deck assembly including aposition sensor that senses a degree of incline of said deck assembly; atelescoping lip assembly including a lip plate with inner and outerends, said telescoping lip assembly supportingly riding on said lipguide rails, said lip plate being movable between retracted and extendedpositions including a continuous range of partially extended positions,said lip plate being in said lip retaining area and downwardly offsetfrom said deck plate when in said retracted and partially extendedpositions, said inner end of said lip plate being in forward alignmentwith said front end of said deck plate when in said extended position,and said lip plate being substantially flush with said deck plate whenin said extended position and resting on the trailer bed; a deckpositioning mechanism secured between said mounting frame and said deckassembly, said deck positioning mechanism including a deck drive rod anddeck solenoid valve to selectively move said deck assembly through saidrange of incline positions; a lip positioning mechanism secured betweensaid deck assembly and said lip assembly, said lip positioning mechanismincluding a lip drive rod and lip solenoid valve to selectively movesaid lip assembly between said retracted and extended positions,including said continuous range of partially extended positions; and, acontrol panel with a programmed CPU in communication with said positionsensor, said CPU being programmed to place said lip solenoid valve in astate to extend said lip drive rod and said lip from said retractedposition to said extended position when said deck assembly is beinglowered and said position sensor senses said deck assembly has reachedsaid preset incline position, and said CPU being programmed to placesaid lip solenoid valve in a state to retract said lip drive rod andsaid lip from said extended position to said retracted position whensaid deck assembly is being raised and said position sensor senses saiddeck assembly has reached said preset incline position.
 2. Thevertically stored telescoping lip leveler of claim 1, and wherein saidcontrol panel includes a circuit board in electrical communication withsaid central processing unit and a number of dock leveler controls. 3.The vertically stored telescoping lip leveler of claim 2, and whereinsaid dock leveler controls include first and second buttons, said firstbutton being selectively engaged to place said deck solenoid valve in astate to extend said deck drive rod and raise said deck assembly towardsaid preset incline position, said CPU being programmed to retract saidlip when said deck assembly reaches said preset incline position andsaid deck assembly continuing to raise to said vertically storedposition, and said second button being selectively engaged to place saiddeck solenoid valve in a state to retract said deck drive rod and lowersaid deck assembly toward said preset incline position, said CPUextending said lip when said deck assembly reaches said preset inclineposition and said deck assembly continuing to lower said deck assemblyuntil said lip engages a bed of a trailer at a trailer engagingposition.
 4. The vertically stored telescoping lip leveler of claim 3,and wherein said dock leveler controls include third and fourth buttons,said third button being selectively engaged to place said lip solenoidvalve in a state to extend said lip drive rod and lip plate, and saidfourth button being selectively engaged to place said lip solenoid valvein a state to retract said lip drive rod and lip plate.
 5. Thevertically stored telescoping lip leveler of claim 1, and wherein saidposition sensor sends a digital signal to said CPU.
 6. The verticallystored telescoping lip leveler of claim 5, and wherein said positionsensor is in electrical communication with said CPU via a wire.
 7. Thevertically stored telescoping lip leveler of claim 6, and wherein theposition sensor is a Hall Effect sensor.
 8. The vertically storedtelescoping lip leveler of claim 7, and wherein said sensor works inunison with a magnet to detect when said lip has returned to its saidretracted position.